The present invention relates to a coatings composition comprising an aqueous dispersion of polymer particles comprising vinyl acetate adsorbed to pigment particles.
Coating formulations are highly complex mixtures of polymers, pigments (most notably TiO2), extenders, and additives. Most opaque or white coatings contain a substantial quantity of TiO2. It is well known that film-forming polymer particles containing phosphate groups can adsorb to TiO2 particles to form composites that improve spacing of the TiO2 particles, which results in a whiter and more opaque appearance of the coating. This improved spacing allows the formulator to reduce the overall level of expensive TiO2.
Especially attractive binders for architectural coatings are polymers (including copolymers) of vinyl acetate, which are known to have high scrub resistance at relatively low cost. Vinyl-acetate polymers that contain phosphate groups would be especially desirable as film forming polymers due to the cost benefits provided by reduced TiO2 usage.
One of the shortcomings of coatings formulations using vinyl acetate based binders is that they tend not to provide adequate stain resistance and stain washability, resulting in the need to touch up a stained surface or even repaint an entire wall. Accordingly, it would be desirable to find a low cost TiO2-adsorbing vinyl acetate based binder that has improved stain resistance and stain-removal properties.